1. Field of the Invention
The present invention relates to a composition for the treatment or prevention of multiple sclerosis comprising 4-carbamoyl-1-.beta.-D-ribofuranosyl imidazolium-5-olate.
2. Description of the Background Art
Multiple sclerosis is a disease involving temporary and multiple disorders in the central nervous system; i.e., disorders in the medullary sheath of the brain, the spinal, and the visual nerve, producing polydomous demyelinating lesions. The disease is clinically found in young adults, and disorders are found in more than one site in the central nervous system, with repeated relapsing and remission. In many cases the initial symptom is decreased visual acuity, followed by motor paralysis, paralysis, gait disturbance, hypersthesia, double vision, and speech disorder [Encyclopedia of Medical Sciences, 31, 53-54 (1982)].
The criterion defined by Multiple Sclerosis Research Team, the Ministry of Health and Welfare, Japan, in 1989 is as follows. (1) At least two lesions are found in the central nervous system, diagnosed based on the symptoms and the views obtained by physical examinations, (2) the relapsing and remission are repeated, and (3) disturbances in the nervous system due to other diseases (e.g cerebrovascular disease, hemangioma, HTLV-I-associated myelopathy, collagen disease, Behget disease, syringomyelia, spino-cerebullar degeneration, cerevical vertebral myelopathy, subacute myelo-optico-neuropathy, syphilis, etc.) are recognized. The diseases completely satisfying all of the above 3 items are deemed the multiple sclerosis confirmed by the clinically diagnosis. Optic neuromyelitis (Devic disease) is considered to be a type of multiple sclerosis.
Although certain immunological disturbances are recognized in multiple sclerosis, the true cause of the disease still remains to be elucidated. For this reason, there are no currently established treatments for the cure of multiple sclerosis. Some reports describe that administration of certain steroid compounds is effective for gradually releasing the symptoms in the acute stage, e.g. administration of dexamethasone, initially about 6 mg/day and gradually decreasing the dose while observing the symptoms, or administration of 20-40 units/dayof ACTH (adrenocorticotrophic hormone) [Neurology, 38(7) 4-89 (1988)]. Other measures proposed for the treatment of multiple sclerosis are rehabilitation during recovery stage, administration of baclofen or dantrolene as a muscle relaxant for decreasing spasticity, or administration of carbamazepine as an anticonvulsant for treating painful tonic seizure. Avoiding strain, common cold, viral infection, and psychic stress are also proposed as measures for the prevention of the relapsing.
However, the most frequently used steroid compounds had a problem of causing serious side-effects such as moon face, cushing syndrome infection, and osteoporosis. The occurrence of side-effects is particularly problematic in the treatment of multiple sclerosis which needs long-term administration of the drugs.
The development of a drug for curing multiple sclerosis which is safe with least side-effects and can be administered to the patients over a long period of time was therefore urgently desired.